using System;
using System.Runtime.InteropServices;
using System.Text;

namespace Vanara.PInvoke
{
	public static partial class Shell32
	{
		/// <summary>Flags used by <see cref="IExtractIcon.GetIconLocation(GetIconLocationFlags, StringBuilder, int, out int, out GetIconLocationResultFlags)"/>.</summary>
		[Flags]
		public enum GetIconLocationFlags : uint
		{
			/// <summary>
			/// Set this flag to determine whether the icon should be extracted asynchronously. If the icon can be extracted rapidly, this
			/// flag is usually ignored. If extraction will take more time, GetIconLocation should return E_PENDING. See the Remarks for
			/// further discussion.
			/// </summary>
			GIL_ASYNC = 0x0020,

			/// <summary>
			/// Retrieve information about the fallback icon. Fallback icons are usually used while the desired icon is extracted and added
			/// to the cache.
			/// </summary>
			GIL_DEFAULTICON = 0x0040,

			/// <summary>The icon is displayed in a Shell folder.</summary>
			GIL_FORSHELL = 0x0002,

			/// <summary>
			/// The icon indicates a shortcut. However, the icon extractor should not apply the shortcut overlay; that will be done later.
			/// Shortcut icons are state-independent.
			/// </summary>
			GIL_FORSHORTCUT = 0x0080,

			/// <summary>
			/// The icon is in the open state if both open-state and closed-state images are available. If this flag is not specified, the
			/// icon is in the normal or closed state. This flag is typically used for folder objects.
			/// </summary>
			GIL_OPENICON = 0x0001,

			/// <summary>Explicitly return either GIL_SHIELD or GIL_FORCENOSHIELD in pwFlags. Do not block if GIL_ASYNC is set.</summary>
			GIL_CHECKSHIELD = 0x0200
		}

		/// <summary>
		/// Flags returned by <see cref="IExtractIcon.GetIconLocation(GetIconLocationFlags, StringBuilder, int, out int, out GetIconLocationResultFlags)"/>.
		/// </summary>
		[Flags]
		public enum GetIconLocationResultFlags : uint
		{
			/// <summary>The physical image bits for this icon are not cached by the calling application.</summary>
			GIL_DONTCACHE = 0x0010,

			/// <summary>
			/// The location is not a file name/index pair. The values in pszIconFile and piIndex cannot be passed to ExtractIcon or
			/// ExtractIconEx. When this flag is omitted, the value returned in pszIconFile is a fully-qualified path name to either a .ico
			/// file or to a file that can contain icons. Also, the value returned in piIndex is an index into that file that identifies
			/// which of its icons to use. Therefore, when the GIL_NOTFILENAME flag is omitted, these values can be passed to ExtractIcon or ExtractIconEx.
			/// </summary>
			GIL_NOTFILENAME = 0x0008,

			/// <summary>
			/// All objects of this class have the same icon. This flag is used internally by the Shell. Typical implementations of
			/// IExtractIcon do not require this flag because the flag implies that an icon handler is not required to resolve the icon on a
			/// per-object basis. The recommended method for implementing per-class icons is to register a DefaultIcon for the class.
			/// </summary>
			GIL_PERCLASS = 0x0004,

			/// <summary>
			/// Each object of this class has its own icon. This flag is used internally by the Shell to handle cases like Setup.exe, where
			/// objects with identical names can have different icons. Typical implementations of IExtractIcon do not require this flag.
			/// </summary>
			GIL_PERINSTANCE = 0x0002,

			/// <summary>The calling application should create a document icon using the specified icon.</summary>
			GIL_SIMULATEDOC = 0x0001,

			/// <summary>Windows Vista only. The calling application must stamp the icon with the UAC shield.</summary>
			GIL_SHIELD = 0x0200, //Windows Vista only

			/// <summary>Windows Vista only. The calling application must not stamp the icon with the UAC shield.</summary>
			GIL_FORCENOSHIELD = 0x0400 //Windows Vista only
		}

		/// <summary>Exposes methods that allow a client to retrieve the icon that is associated with one of the objects in a folder.</summary>
		// https://msdn.microsoft.com/en-us/library/windows/desktop/bb761854(v=vs.85).aspx
		[PInvokeData("Shlobj_core.h", MSDNShortId = "bb761854")]
		[ComImport, Guid("000214fa-0000-0000-c000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
		public interface IExtractIcon
		{
			/// <summary>Gets the location and index of an icon.</summary>
			/// <param name="uFlags">One or more of the following values. This parameter can also be NULL.use GIL_ Consts</param>
			/// <param name="szIconFile">
			/// A pointer to a buffer that receives the icon location. The icon location is a null-terminated string that identifies the file
			/// that contains the icon.
			/// </param>
			/// <param name="cchMax">The size of the buffer, in characters, pointed to by pszIconFile.</param>
			/// <param name="piIndex">A pointer to an int that receives the index of the icon in the file pointed to by pszIconFile.</param>
			/// <param name="pwFlags">A pointer to a UINT value that receives zero or a combination of the following value</param>
			/// <returns>
			/// Returns S_OK if the function returned a valid location, or S_FALSE if the Shell should use a default icon. If the GIL_ASYNC
			/// flag is set in uFlags, the method can return E_PENDING to indicate that icon extraction will be time-consuming.
			/// </returns>
			[PreserveSig]
			HRESULT GetIconLocation(GetIconLocationFlags uFlags, StringBuilder szIconFile, int cchMax, out int piIndex, out GetIconLocationResultFlags pwFlags);

			/// <summary>Extracts an icon image from the specified location.</summary>
			/// <param name="pszFile">A pointer to a null-terminated string that specifies the icon location.</param>
			/// <param name="nIconIndex">The index of the icon in the file pointed to by pszFile.</param>
			/// <param name="phiconLarge">
			/// A pointer to an HICON value that receives the handle to the large icon. This parameter may be NULL.
			/// </param>
			/// <param name="phiconSmall">
			/// A pointer to an HICON value that receives the handle to the small icon. This parameter may be NULL.
			/// </param>
			/// <param name="nIconSize">
			/// The desired size of the icon, in pixels. The low word contains the size of the large icon, and the high word contains the
			/// size of the small icon. The size specified can be the width or height. The width of an icon always equals its height.
			/// </param>
			/// <returns>Returns S_OK if the function extracted the icon, or S_FALSE if the calling application should extract the icon.</returns>
			void Extract([MarshalAs(UnmanagedType.LPTStr)] string pszFile, uint nIconIndex, out IntPtr phiconLarge,
				out IntPtr phiconSmall, uint nIconSize);
		}
	}
}